Field of the Invention
The present invention relates generally to a cable-driven parallel robot capable of changing a workspace. More particularly, the present invention relates to a cable-driven parallel robot capable of changing a workspace, in which the cable-driven parallel robot is provided with an end effector having a plurality of modules that can efficiently move to upper and side parts of an object without interference.
Description of the Related Art
Up to now, many robots used in applied fields of industrial robots have been developed.
Generally, a widely-known serial robot has a structure in which joints and links are alternately connected to each other in series, and can realize a large workspace, various working positions, and multi-postures. However, a payload of the serial robot is low and the workspace thereof is limited to its arm length.
To the contrary, a parallel multi-joint robot in which joints, links, and support parts are configured to have a parallel structure can perform work with high precision, high speed, and high payload capacity in a relatively small workspace.
Such a parallel robot is a robot, in which a platform corresponding to an end effector of a robot manipulator and a base fixed to a foundation are connected to each other by multiple links including a linear or rotational drive device so as to have a closed-loop structure.
Meanwhile, the serial robot as mentioned above has an advantage in that it has links serially connected to each other, and a large workspace in which an end effector can operate. However, the serial robot has a limitation in that it is susceptible to structural changes due to bending at the links and joints, whereby it may have low precision. Furthermore, the payload of the serial robot is very limited compared to weight of the serial robot itself.
However, although the parallel robot has a workspace smaller than the serial robot, it can solve problems of the serial robot mentioned above, and greatly increase work precision. Accordingly, use of the parallel robot is gradually on the rise.
In this case, a cable-driven parallel robot that can simultaneously solve the problem of the parallel robot in ensuring a workspace, and the problem of the serial robot in securing sufficient payload has been developed.
The cable-driven parallel robot (CDPR) is a device capable of performing various work tasks by changing the position of the end effector by winding or unwinding cables. As shown in FIG. 1, the cable-driven parallel robot is provided with frames 10 having a plurality of connecting points, and an end effector 30 whose position is changed by winding or unwinding each of cables 20.
The cable-driven parallel robot having the above-mentioned configuration can efficiently control the position of the end effector 30 in a limited space, and when each of the connecting points of the frames 10 is installed in a widely distributed way, a usable workspace may become large, thereby increasing workspace efficiency.
However, as shown in FIG. 2, when the cable-driven parallel robot is configured to have a shape of a complete enclosed space, a portion of an object or neighboring structures in a workspace interfere with an end effector of the parallel robot, which impedes the range of the end effector, thereby reducing the workspace.
For example, when cleaning an upper surface of a roof of a large-sized bus, upper end corners of left and right sides of the bus may interfere with lower cables of a cable-driven parallel robot having eight cables, thereby making access to the upper surface of the roof difficult.
Of course, to avoid such interferences, a cable-driven parallel robot may be provided on each side frame. However, this solution increases cost, and reduces efficiency due to structural problems.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.